Electron discharge device control system



Jane 25, 1938. A. GAUDENZI 2,106,524

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed Janv 11, 1934 2 Sheets-Sheet l Jan. 25, 1938. A. GAUDENZI 2,106,524

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed Jan. 11, 1934 2 Sheets-Sheet 2 Patented Jan. 25, 1938 uurrso STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Switzerland Application January 11, 1934, Serial No. 706,189 In Germany January 20, 1933 9 Claims.

This invention relates in general to the control of electron discharge devices and more particularly to means for initiating the flow of current though the anodes of an electron discharge device of which the cathode is not continuously maintained in an electron emitting condition.

In electron discharge devices not provided with means for continuously exciting the cathode, it is necessary to establish the electron emitting condition of the cathode every time the flow of current is to occur therethrough and, if the device is provided with a plurality of anodes carrying current in nonconsecutive sequence, it is likewise necessary to establish the electron emitting condition of the cathode every time the flow of current though each anode is to be initiated. It is not generally desirable nor even possible to use mechanical means to obtain such result, and it is preferred to cause electron emission at the cathode by impressing a suitable electromotive force between the cathode and another electrode which may be one of the main anodes oi? the device. It is then desirable to reduce the dielectric strength of the space adjacent the cathode while r maintaining a space of high dielectric strength between the anodes to thereby facilitate the establishment of the discharge between an anode and a cathode while preventing the establishment of a discharge between anodes. In electron discharge devices of the vapor type, such resuit is preferably obtained by increasing the vapor density in the neighborhood or the cathode by means of a blast of vaporized operating fluid.

It is, therefore, among the objects of the present invention to provide a control system for an electron discharge device of the vapor type in which the cathode is not continuously maintained in an electron emitting condition.

Another object of the present invention is to provide a control system for an electron discharge device of the vapor type whereby the cathode is brought to conductive condition each time the flow of current is to be initiated through an anode.

Another object of the present invention is to provide a control system for an electron discharge device of the vapor type in which the dielectric strength of the space adjacent the oathode is maintained at a low value.

Another object of the present invention is to provide a control system for an electron discharge device of the vapor type in which the flow of current through each anode is initiated by a source other than the source of supply of the device.

Objects and advantages, other than those above described will be apparent, from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 diagrammatically illustrates one embodiment of the present invention applied to the control of a group of electric valves utilized for transmitting energy between an alternating current line and a direct current line and in which the flow of anode currents are initiated by impressing potential impulses on the anodes;

Fig. 2 is an enlarged cross-sectional view of a portion of the cathode and of the fluid vaporizing means utilized in the several embodiments of the invention herein illustrated and described;

Fig. 3 diagrammatically illustrates a portion of a modified embodiment of the present invention in which the anode currents of a polyphase discharge device are initiated by impressing potential impulses on control electrodes and on an auxiliary anode of the device; and

Fig. 4 diagrammatically illustrates another modified embodiment of the present invention differing from the embodiment illustrated in Fig. 3 in that the auxiliary anode of the device receives potential impulses only when the current flowing through the device is below a predetermined limit.

Referring more particularly to the drawings by characters of reference, reference numeral 6 designates a three phase alternating current line which is utilized either as supply circuit or as output circuit in the several embodiments herein illustrated and described, being associated with electric valve means utilized for converting current between line 6 and a direct current line 1, 8. Line 6 is, accordingly, connected with a supply transformer 9 having a secondary winding connected with direct current conductor I either directly or through an interphase transformer l I. The secondary winding of transformer 9 comprises a plurality of phase displaced portions severally connected with the anodes 12 of a plurality of electron discharge devices generally designated by l3, each having a cathode l4 connected with direct current conductor 8. The valves may be of any suitable construction in which the flow of current occurs through a gas or vapor at suitable pressure, and may be provided with the usual cooling and evacuating means which may be indi- Each anode is connected with a segment of a distributor I6 having a brush connected with conductor 8 through a capacitor I'I. Each of the segments of distributor I6 connected with an anode is adjacent another segment connected with the positive terminal of a source of direct current such as a generator I8 having the negative terminal thereof connected with conductor 8. The brush of distributor I6 is operated in relation to the voltage cycle of line 6 in any suitable manner such as, for instance, by means of a synchronous motor I9 energized from line B. The engagement of the brush with the several segments of the distributor may be adjusted with respect to the voltage cycle of line 6 by movement of a lever 20 by means of which the segments may be spatially displaced.

In the present embodiment, it is assumed that the operating fluid of the valves is mercury vapor and that cathode I4 is constituted by a body of mercury in the liquid state. As is more clearly illustrated in Fig. 2, vaporized mercury is produced in a boiler 2I provided with suitable heating means such as a heating resistor 22 energized from a battery 23 or other suitable source of potential. The boiler communicates with the well or container portion 24 for the liquid mercury by means of a pair of pipes 26 and 21 constituting an exhaust passage for vaporized mercury from the boiler and a return passage for condensed mercury respectively. The joints between the several portions of the structure are of any suitable kind providing a gas tight connection therebetween and are preferably obtained by welding. It will be understood that the boiler may be covered with heat insulating material and that the well 24 will generally be provided with a suitable water jacket. Pipe 26 is provided with a nozzle portion 28 to project the mercury vapor into the space above and adjacent the liquid cathode. The nozzle may project above the level of cathode I4, but it was found that the nozzle could be operated even when immersed under a material height of mercury. Pipe 21 is provided with an elbow portion 29 to constitute a siphon to return condensed mercury from cathode I4 into boiler 2|. Nozzle 28 and elbow 29 are preferably made of refractory material, such as tungsten or quartz, which is not affected by the mercury vapor or by liquid mercury. If members 28 and 29 are made of refractory metal they may serve as point of attachment for the discharge whereby the flow of current through the valve may be rendered more stable.

In operation, the space adjacent the cathode of each valve receives a blast of operating vapor from the associated boiler of such intensity as to cause such space to have a dielectric strength materially lower than the dielectric strength of the remainder of the space within the valve. As a result of such adjustment, upon impression of a suitable electromotive force between each anode and the associated cathode, an electron emission will occur at the cathode by production of a so-called cathode spot Whereas an electron emission cannot be established at the anode. Although the fiow of current between the anode and the cathode can therefore be initiated upon impression of a relatively low potential on the anode, such potential will not cause a loss of the valve action of the device or backfire.

Assuming that energy is to be transmitted from line 6 to line I, 8, line 6 supplies current to transformer 9 which impresses potentials on the anodes of the valves in recurring sequence. Such energization of the anodes, however, occurs at potentials which are not sufficient to cause the flow of current between the anodes and the associated cathodes to be established. Motor I9 drives the brush of distributor iii to repeatedly charge capacitor I! from generator I8 and to sequentially discharge the capacitor through the several valves by severally connecting the terminals thereof with the anodes of the valves. Lever 20 is so adjusted that each anode is momentarily connected with capacitor I? to receive a potential impulse therefrom while receiving, from transformer 9, a potential higher than the potentials of the other anodes. The potential impressed on the anode by capacitor I! is so chosen that the space adjacent the associated cathode is thereby stressed beyond its dielectric strength, electronic emission is established at the cathode and a discharge occurs between the anode and the cathode. The fiow of current is thereby released from transformer 9 through the anode to the cathode and such flow continues until the anode becomes negative with respect to the associated cathode as a result of the variable energization thereof from transformer 9 or of the initiation of the discharge through another of the anodes.

Such sequence of operation is repeated for each valve during the voltage cycle of line 6 to cause a flow of rectified current to occur through conductors I and 8. The output voltage of the system may be varied by adjustment of lever 20, such adjustment causing the flow of current through each anode to be initiated at a variable time of the voltage cycle of line 6. of current through each anode is initiated at times later than a predetermined time interval before reversal of the voltage impressed on such anode by the transformer, the flow of current through the anode will cease before a flow of boiler 2| reduces the dielectric strength of the vapor within the space adjacent each cathode by producing a relatively high vapor density within such space by means of vaporized operating fluid previously condensed Within the valve.

Capacitor I1 and distributor I6 constitute means for sequentially impressing potentials on the anodes of such sign and magnitude as to cause initiation of discharges between the anodes and the cathode and at such recurring intervals as to release the flow of current between line 6 and line I, 8, sequentially through the several valves. Distributor I6 is controlled in response to an operating condition of the valves which is the frequency of the voltage of line 6 as also is the operation of the brush of distributor I6 from motor I9.

In the embodiment illustrated in Fig. 3, the several valves are replaced by a single electron discharge device 3| provided with a cathode 32 similar to cathode 24 and associated with boiler 2I in the manner above described. In the present embodiment, each anode I2 is associated with a control electrode as designated at 33 connected through resistors such as 34 and 36 with the negative terminal of a source of potential such ill) as a battery 31 having the positive terminals thereof connected with conductor 8. A second battery 38 has the negative terminal thereof connected with conductor 8 and is sequentially connected with the several control electrodes through a second distributor 39 and resistors 34. Distributor 39 is provided with a brush preferably driven by motor 9, and the operation thereof may be adjusted by means of lever 4|.

In the present embodiment, generator I8 is replaced by a rectifying device 44 connected with line 6 through a transformer 43, such system constituting a convenient means for obtaining the high potential difference which may be necessary for charging capacitor H. The discharge segments of distributor 6 may be interconnected and connected with an auxiliary anode 42 of device 3|, such anode being preferably within the space to be brought to low dielectric strength adjacent the cathode to facilitate the initiation of a discharge between the anodes and the oathode. The energization of resistor 22 from battery 23 may be controlled by relays 5| and 52 operating in response to the vapor density at a suitable point of device 3|, for instance, in the neighborhood of anode 42. Such result is obtained by connecting, at such point, a suitable pressure measuring device such as a system comprising a pair of resistors 46 and 41 arranged to be subjected to such pressure and cooperating with a pair of resistors 48 and 49 arranged in space at atmospheric pressure, such resistors forming a Wheatstone bridge energized from battery 23 for impressing, on relays 5| and 52, voltages depending on the vapor pressure about resistors 46 and 41.

In the absence of distributor I6 and anode 42, the flow of current through the several anodes is released by the impression of a positive potential from battery 38 on the several control electrodes 33, each control electrode momentarily operating as an anode receiving, from battery 38, a potential of sufiicient magnitude to cause breakdown of the dielectric within the space between such control electrode and the cathode and establishment of a cathode spot at the cathode. As in the embodiment illustrated in Fig. 1, the flow of current through the several anodes may be overlapping, consecutive or discontinuous. If distributor 6 and anode 42 are present, the cathode spot is established by the joint action of the dis charges at the control electrodes and at anode 42. If the flows of current through the several anodes overlap or are consecutive, the cathode spot will remain irrespective of the action of the control electrodes and of anode 42. Under either condition of operation the output voltage of the system will be regulated by adjustment of lever 4| to vary the time in the voltage cycle at which each control electrode releases the flow of current through the associated anode. In general, it will be advantageous to initiate the discharge simultaneously through anode 42 and one of the control electrodes but such adjustment may be departed from by separately adjusting levers 20 and 4|.

If the vapor density in the space adjacent anode 42 is insufficient, a large potential difference is impressed on the coils of relays 5| and 52 which close the contacts thereof to effect direct connection of resistor 22 with battery 23. When the vapor density reaches a predetermined value the potential impressed on the coils of the relays decreases to an extent such that relay 52 operates to insert a resistor in series with resistor 22. If

the vapor density increases further, relay 5| will operate to completely deenergize resistor 22. In such a manner a substantially uniform vapor density may be maintained in the space adjacent anode 42 and cathode 32 irrespective of the magnitude of the flow of current through device 3|. The operation of boiler 2|, which constitutes means for reducing the dielectric strength of the vapor within the space adjacent cathode 22, is thus controlled in response to an operating condition of device 3|, such condition being the vapor density at any selected point thereof.

In the embodiment illustrated in Fig. 4, the control electrodes are again generally maintained negative with respect to cathode 32 by means of a battery 31 but the potential impulses initiating discharges from the control electrodes and anode 42 to the cathode are supplied from a high frequency source such as a synchronous generator 53 driven by motor l9. Generator 53 is preferably connected between conductor 8 and the brush of distributor 39 to impress a comparatively low potential on the control electrodes and is preferably connected with anode 42 through a step-up transformer 54. As is well known, when the flow of current through a device such as device 3| falls to a low value the cathode spot is not cer-' tain to be maintained although the anode currents may be consecutive or even overlap. Such cathode spot must therefore be reestablished at every operating period of the anodes, preferably by the combined action of the control electrode and of anode 42. When the current is at a higher value the action of control electrode 42 may be omitted and such anode is, accordingly, connected with transformer 54 through an auxiliary electric valve 56. Valve 56 is provided with a control electrode receiving a bias potential from a battery 51 of such sign and magnitude as to render the valve conductive, and receiving a negative potential varying in response to the magnitude of the flow of current through device 3|. To obtain such result, the cathode of valve 56 may be connected with battery 51 through a resistor 6| receiving current from a current transformer 58 inserted in the connection of line 6 with transformer 9, through a rectifying device 59 and a smoothing reactor 62. When the flow of current through device 3| is at a low value, valve is maintained conductive by the action of battery 51. When the flow of current through device 3| increases above a predetermined value the control electrode of valve 56 is brought to a potential such that valve 56 becomes non-conductive and the anode 42 is thereby made inoperative. The transformer 54, which constitutes a source of potential connected between electrode 42 and cathode 32 to initiate a discharge therebetween, is thus controlled in response to an operating condition of device 3| which is the magnitude of the flow of current therethrough.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In combination, electron discharge means of the condensable vapor typehaving fixed electrodes including an anode and a cathode, means for vaporizing operating fluid condensed within said discharge means, means for introducing the Vaporized fluid within the space adjacent the cathode to decrease the dielectric strength of such space, a source of potential connected between one of the electrodes and the cathode to initiate a discharge therebetween, and a second source of potential connected between the anode and the cathode to cause a flow of current to occur therebetween upon initiation of the discharge from the first said source, and means responsive to an operating condition within said discharge means controlling the second said means.

2. In a system for transmitting energy between electric circuits comprising a polyphase inductive winding and a vapor type electron discharge device cooperating therewith for interconnecting said circuits, said discharge device having anodes each associated with a control electrode, an auxiliary anode and a cathode, means for reducing the dielectric strength of the space adjacent said cathode, and means for sequentially impressing potentials on the control electrodes and intermittently on said auxiliary anode of such signs and magnitudes as to cause initiation of discharges between the anodes and the cathode and at such recurring intervals as to release the flow of current between said circuits sequentially through said anodes.

3. In combination, electron discharge means of the low pressure vapor type having fixed elec trodes including an anode and a cathode, means for reducing the dielectric strength of the space adjacent the cathode, a source of potential connected between one of the electrodes and the cathode to initiate a discharge therebetween, and a second source of potential connected between the anode and the cathode to cause a flow of current to occur therebetween upon initiation of the discharge from the first said source, and means responsive to an operating condition within said discharge means for controlling the action of the first said source.

4. The combination with an electron discharge device comprising a main anode, an auxiliary anode and a cathode of vaporizable material, of means for vaporizing material of said cathode to reduce the dielectric strength of the space thereabout, means comprising a source of current connected with said auxiliary anode and cathode for initiating discharges therebetween, a second source of current connected with said main anode and said cathode to cause a flow of current therebetween upon initiation of said discharge, and means operable responsive to and in dependence on the vapor pressure within said device for controlling the action of the first said means.

5. The combination with an electron discharge device comprising a plurality of main anodes, an auxiliary anode and a cathode, of means for vaporizing material of said cathode to reduce the dielectric strength of the space thereabout, m ans comprising a source of current for exciting said auxiliary anode, a source of alternating current having connections with said main anodes and said cathode to cause flow of current therebetween upon initiation of said discharges, means for continually connecting the first said source of current with said auxiliary anode to cause discharges therefrom to said cathode during such moments relative to the voltage frequency of the second said source of current as to cause the flow of current sequentially through said main anodes to said cathode, and means operable responsive to and in dependence on the vapor pressure within said device for controlling the operation of the first said means.

6. The combination with an electron discharge device comprising an evacuated chamber containing an electrode of vaporizable material, of means for vaporizing material of said electrode to reduce the dielectric strength of the space thereabout, and means operable responsive to and in dependence on the pressure of said vaporized material for controlling the operation of the first said means.

7. The combination with an electron discharge device comprising an evacuated chamber containing an electrode of vaporizable material, of means for vaporiz ng material of said electrode to reduce the dielectric strength of the space thereabout, and means operable responsive to and in dependence on the pressure of said vaporized material for varying the operation of the first said means, to thereby control the rate of vaporization of said material.

8. The combination with an electron discharge device comprising an evacuated chamber containing an electrode of vaporizable material, of means comprising a source of current and an element heated thereby for vaporizing material of said electrode to reduce the dielectric strength of the space thereabout, means comprising an electric bridge having an arm thereof variable responsive to and in dependence on variations in the pressure of said vaporized material, and means operable responsive to said variations of said arm for varying the connections of said source with the first said means, whereby the pressure of said vaporized material is controlled.

9. The combination with electron discharge means of the low pressure vapor type comprising a cathode and a plurality of electrodes including an anode, a control electrode, and an ignition anode severally disposed in fixed spaced relation, of means other than said electrodes for reducing the dielectric strength of the space adjacent said cathode, a source of potential connected with said ignition anode and cathode operable to cause a discharge to be initiated therebetween upon occurrence of said reduction of the dielectric strength adjacent said cathode, a second source of potential connected with said control electrode and cathode operable to cause a discharge to be initiated therebetween re-l sponsive to the said discharge between said ignition anode and cathode, and a source of potential connected with the first said anode and cathode operable to cause a flow of current to be initiated therebetween responsive to the said discharge between said control electrode and cathode.

ARTHUR GAUDENZI, 

